Apparatuses for cutting vegetation have been available commercially for years. They are also-called motor scythes and are used in particular for trimming grass in edge areas. The spool of such an apparatus can be found for example in U.S. Pat. No. 4,097,991.
In order to adjust the constantly wearing cutting thread to the desired working length, the spool element in such an apparatus is drawn downward against the force of the spring, causing the pegs on the spool element to be drawn out of the recesses in the spool housing so that the spool element can be rotated and the cutting thread, for example a plastic thread, thus unwound. When enough thread has been unwound, the spool element is locked to the spool housing so as to rotate in unison again by engagement of the pegs in the recesses.
The spring, which loads the spool element against the spool housing and thus holds the pegs in the recesses, at the same time presses the spool housing against the polygon on the driving pin which connects the spool housing with the driveshaft so as to rotate in unison. Grass stalks and similar plant parts unavoidably wind themselves in the narrow gap between the spool housing and the protective disk around the driveshaft. Increasing winding around the driveshaft causes the spool housing to be pushed downward away from the gearhead and thus the spring to be more and more compressed. The compression of the spring can become so great that one can no longer draw the spool element downward far enough to unlock it from the spool housing by disengaging the pegs from the recesses when one wants to adjust the cutting thread. One ten has no choice but to unscrew the nut at the lower end of the driving pin and take off the spool to remove the firmly wedged grass wound around the driveshaft.
If one is mowing in an area with hard objects such as stones or a wire fence, the cutting thread is worn especially greatly. It can then happen that the cutting thread must be adjusted every few minutes but the release between spool element and spool housing is blocked by jammed grass stalks. One must then frequently spend more time cleaning the driveshaft than actually mowing.
Apparatuses are also known wherein the spool with the cutting thread can be replaced by another cutting tool, e.g. a so-called grass striking plate which is formed like a circular saw blade. In apparatuses which can be equipped with such a grass striking plate, a pressure disk permitting the striking plate to be clamped in presses against the protective disk from below.